2004 KV18 - A visitor from the Scattered Disk to the Neptune Trojan population

TL;DR

This study analyzes the dynamical instability of the Neptunian Trojan 2004 KV18, revealing it is a temporary capture likely originating from the Scattered Disk, providing insights into small body transfer processes in the outer Solar System.

Contribution

It is the first detailed dynamical analysis showing 2004 KV18 as a highly unstable, temporary Neptunian Trojan originating from the Scattered Disk, unlike more stable primordial Trojans.

Findings

2004 KV18 is on a highly unstable orbit

Most test particles leave the Trojan region within 0.1-0.3 Myr

Half of the particles are ejected from the Solar System within 37 million years

Abstract

We have performed a detailed dynamical study of the recently identified Neptunian Trojan 2004 KV18, only the second object to be discovered librating around Neptune's trailing Lagrange point, L5. We find that 2004 KV18 is moving on a highly unstable orbit, and was most likely captured from the Centaur population at some point in the last ~1 Myr, having originated in the Scattered Disk, beyond the orbit of Neptune. The instability of 2004 KV18 is so great that many of the test particles studied leave the Neptunian Trojan cloud within just ~0.1 - 0.3 Myr, and it takes just 37 million years for half of the 91125 test particles created to study its dynamical behaviour to be removed from the Solar system entirely. Unlike the other Neptunian Trojans previously found to display dynamical instability on hundred million year timescales (2001 QR322 and 2008 LC18), 2004 KV18 displays such extreme instability that it must be a temporarily captured Trojan, rather than a primordial member of the Neptunian Trojan population. As such, it offers a fascinating insight into the processes through which small bodies are transferred around the outer Solar system, and represents an exciting addition to the menagerie of the Solar system's small bodies.